Shear fingers for sickle bars

ABSTRACT

Pointed shear fingers are formed, preferably in multiples, from a flat metal plate which is blanded out to the required outline. The blank is formed in a die which offsets the projecting finger portions and simultaneously creates a convexity of the bottom surface bordered by angled edges or bevels, the forming also producing a concavity in the top of each finger, leaving a flat V-shaped marginal portion which provides shearing edges in conjunction with the formed bevels of the bottom side. Shear fingers are separated by clean-out recesses which are formed in the blanking operation.

United States Patent 1 1 1111 3,716,978 Haban 1 Feb. 20, 1973 541 SHEAR FINGERS FOR SICKLE BARS 2,278,393 3/1942 Vut z ..56/3l0 x 1 1 1mm Joseph e & Marquette 23331323 511322 "2232; 5211131111: 1111113122133; Streets, Ra1I1e,w1S-5344 2,882,672 4/1959 Naery ..56/307 [22] Filed: May 8, 1972 u Primary Exammer-Russell R. Kmsey PP 251,249 V Att0rney-Arthur L. Morsell, Jr. et al.

Related US. Application Data 57] ABSTRACT [62] g g' g i 1970 Pointed shear fingers are formed, preferably in multiples, from a flat metal plate which is blanded out to the required outline. The blank is formed in a die Q I n a I c I I I o u a a a n u I a u c I a u u I v A o e u a a e I I I n l t.l ..56 2 6 3 taneously creates a convexity of the bottom Surface Fle d 0 Search l 9 b de g d edges o e e the o m g a s producing a concavity in the top of each finger, leav- [56] References cued ing a flat V-shaped marginal portion which provides UNITED STATES PATENTS shearing edges in conjunction with the fonned bevels of the bottom side. Shear fingers are separated by l05,3ll 7/1870 Crosby ..56/3l0 clean-out recesses which are formed in the blanking 173,851 211876 Freeman ..56/298 operation 520,807 6/1894 Shipley ..56/3ll 1,726,378 8/1929 Barber ..56/3l0 8 Claims, 8 Drawing Figures PMENIED FEBZO I975 SHEET 2 OF 2 SHEAR FINGERS FOR SICKLE BARS This application is a division of appIicationSer. No. 56,427, filed July 20, 1970 and now US. Pat. No. 3,682,021.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to shear fingers, often referred to as guards, which are used in mowers, swathers, and combines operating with a sickle bar.

2. Description of the Prior Art Heretofore some shear finger elements have been formed in two pieces, one part comprising a soft iron casting or steel forging which included a mounting portion to lock up against the fixed bar of the asseinbly. The soft iron casting or steel forging also included an integral projecting portion to form a support for a ledger plate or blade which had to be riveted or otherwise secured to the projection. The ledger plates or blades, in the type of conventional construction, were made of high carbon material so that they could be heat treated, and the edges of the top surface of blade had to be specially machined at an angle, and the entire top surface of. the blade had to be ground to produce the opposed shearing edges. There was a great deal of labor involved in the above procedure which increased the expense.

Some shear fingers have been one-piece steel forgings, but here the shearing edges had to be separately machined to provide bevels and then machined on the other side. This type of construction was also very expensive. In the conventional arrangements, because of the methods employed, the shear fingers were usually manufactured in singles.

SUMMARY OF THE INVENTION The present invention provides a specially shaped finger where there is a flat V-shaped marginal portion orrthe top of each finger which provides shearing edges in conjunction with bevels on the underside of the blade.

A general object of the invention is to provide an improved shear finger as above outlined.

A further object of the invention is provide a shear finger element wherein the shear fingers are separated by clean-out recesses.

Other objects of the invention are to provide shear finger elements which are siniple in construction, inexpensive to manufacture, efficient in operation, and well adapted for the purposes described.

With the above and other objects in view, the invention consists of the improved shear fingers for sickle bars, and all of its parts, combinations, and steps, as set forth in the claims, and all equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings, illustrating one complete embodiment of the preferred form of the invention, in which the same reference numerals designate the same parts in all of the views:

FIG. I is a plan view of a portion of the blank for forming the shear fingers;

FIG. 2 is a plan view of a completed shear finger;

FIG. 3 is an end view thereof;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 2;

FIG. 6 is a perspective view showing a fragment of the top side of a sickle bar assembly;

FIG. 7 is a perspective view showing a fragment of a sickle bar assembly, looking principally at the opposite side from FIG. 6; and

FIG. 8 is an elevational view, partially diagrammatic, of the die forming apparatus, showing a blank about to be formed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, the improved shear finger elements are preferably manufactured from a flat plate of medium carbon steel (C-l045). In order to effect economy in manufacture it is preferred to form the shear fingers in multiples such as the doubles illustrated in FIG. 1, and to arrange to produce rows of elements with interfitting sets of fingers from a single strip of flat material. In FIG. 1 the numeral 20 designates an element with a mounting portion 16 carrying a pair of shear fingers 21 as cut from one side of a strip, and the numeral 20a another element in reverse position, so that the finger projections 21 on one side are interfitting with the finger projections 21a from the other side. The blanks 20 with the sets of fingers are cut by being passed through a conventional blanking die which blanks them out to the shape shown at 20 or 2011 and simultaneously pierces the holes 18 and 19, the material between the interfitting fingers being discarded. The blanks are then preferably heated and fed into a forming die having a punch portion 10 and a die portion 11 as shown in FIG. 8 and formed to the shape shown in FIGS. 2-5, inclusive. The forming die offsets the finger portions 21, as is clear from FIG. 3, there being a shoulder 30 at each offset. The central portion-of the bottom of each finger portion is rendered convex in the forming operation as at 22 (FIG. 4) and simultaneously the forming die produces the bevelededges 23 as shown in FIG. 4, no special machining being needed for the bevels. At the same time a concavity 24 is produced in the top side, which concavity is bordered by flat edge and tip portions 25 arranged in V-shape in plan view as in FIG. 2. The material is also offset around the holes 18 as at 17 (FIG. 3). The concavity 24 creates relief between the flat margins 25, separating the two flat surfaces.

These flat surfaces 25 are then ground in a single grinding operation to produce the shearing edges 26 in conjunction with the bevels 23 which were produced solely by the forming operation. The grinding may be done orrthe flat face 'of a rotating stone. No grinding on the bottom face is required. In addition, forming of the angled portions 23 in the forming die creates a built-in roughness at the edges 26 which is somewhat helpful in the shearing operation as it tends to hold fine grasses while they are being sheared so that they do not slip out.

Each of the formed elements 20, immediately after forming, is then heat treated to harden the finger areas 21, by quenching in a quenching medium to a hardness of RC50-55.

The concavo-convex portion of each finger adds substantial strength and makes it possible to provide sufficiently strong fingers from a blank as thin as 0.1793 of an inch.

The improved shear finger. elements are rigidly mounted on the sickle bar assembly by means of nuts and bolts 33 which pass through the assembly in the usual manner as shown in FIGS. 6 and 7. The movable knife is constructed in the conventional manner and comprises a plurality of V-shaped blades 27 connected together by a knife-back bar 28 which moves within the space 29 inwardly of the shoulders 30 at the inner ends of the offset shear fingers. Hold-down clips 31 are bolted to the assembly and serve to maintain the movable blades in shearing contact with the fixed shear fingers to maintain the relationship. It is to be noted that the hold-down clips are relatively long with respect to conventional practice, overlapping at least two blades, and with this arrangement uniform clearances between the upper and lower knives are more accurately maintained. Each hold-down clip has a large central opening 32 for clearance of portions of the clippings.

The sickle bar of FIGS. 6 and 7 will be otherwise supported and operated in the same manner disclosed in my US. Pat. No. 3,364,666, dated Oct. 9, 1964.

With the improved method of the present invention it is obvious that shear fingers can be manufactured more economically than with methods which require casting or forging operations, as such castings or forgings have required additional machining on both the top and bottom surfaces of the fingers. With the present invention the novel forming method makes it possible to maintain closer tolerances than has heretofore been practical in forging or casting methods. In addition, with the present method of procedure, any desired number of shear fingers may be formed integral with a single element, with the latter having any selected length. This feature is particularly useful for small sickle bars where, with the present method, all of the shear fingers may be readily formed integrally as a single unit.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

What I claim is:

1. A shear finger element for a sickle bar comprising a mounting portion and a finger portion projecting therefrom, said finger portion having an interior of concavo-convex shape to provide a concave upper side and a convex lower side, said convex side having beveled edge portions and said concave side having flat edge portions which along with the beveled margins define shearing edges.

2. A shear finger element as claimed in claim 1 in which said finger portion is offset from the plane of the mounting portion.

3. A shear finger element as claimed in claim 1 in which the finger portions are triangular in plan view with projecting points, and in which the beveled edge portions and the flat edge portions converge to said point.

4. A shear finger element as claimed in claim 1 in which the mounting portion is rectangular, and in which there are a plurality of spaced finger portions projecting from said mounting portion, and in which there is a cut-out recess in an edge of the mounting portion between finger portions.

5. A shear finger element as claimed in claim 4 in which the finger portions are offset from the plane of the mounting rtion.

6. A shear ger element as claimed in claim 1 m 

1. A shear finger element for a sickle bar comprising a mounting portion and a finger portion projecting therefrom, said finger portion having an interior of concavo-convex shape to provide a concave upper side and a convex lower side, said convex side having beveled edge portions and said concave side having flat edge portions which along with the beveled margins define shearing edges.
 1. A shear finger element for a sickle bar comprising a mounting portion and a finger portion projecting therefrom, said finger portion having an interior of concavo-convex shape to provide a concave upper side and a convex lower side, said convex side having beveled edge portions and said concave side having flat edge portions which along with the beveled margins define shearing edges.
 2. A shear finger element as claimed in claim 1 in which said finger portion is offset from the plane of the mounting portion.
 3. A shear finger element as claimed in claim 1 in which the finger portions are triangular in plan view with projecting points, and in which the beveled edge portions and the flat edge portions converge to said point.
 4. A shear finger element as claimed in claim 1 in which the mounting portion is rectangular, and in which there are a plurality of spaced finger portions projecting from said mounting portion, and in which there is a cut-out recess in an edge of the mounting portion between finger portions.
 5. A shear finger element as claimed in claim 4 in which the finger portions are offset from the plane of the mounting portion.
 6. A shear finger element as claimed in claim 1 in which the concave upper side has a relatively shallow concavity in the central portion only, and in which the flat edge portions of said concave side are inwardly of the outline of the finger.
 7. A shear finger element as claimed in claim 1 in which the flat edge portions on the concave side are ground. 